Method and Apparatus for Scanning Access Point in Wireless LAN System

ABSTRACT

The present disclosure relates to obtaining AP information or information on a channel where the AP is positioned from a neighboring mobile terminal that has recently performed AP scanning and re-attempting to scan based on the obtained information. According to an embodiment of the present disclosure, a method for scanning an access point (AP) in a wireless local area network (LAN) system comprises performing first WLAN scanning by a first mobile terminal, transmitting a request for WLAN AP information to a second mobile terminal that has previously performed WLAN AP scanning, receiving the WLAN AP information from the second mobile terminal, and performing second WLAN scanning based on the WLAN AP information.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(a) of a Koreanpatent application filed in the Korean Intellectual Property Office onJul. 31, 2014 and assigned Serial No. 10-2014-0098353, the entiredisclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure concerns methods and apparatuses for scanningaccess points in wireless LAN systems.

BACKGROUND

In order to meet the demand for wireless data traffic soaring since the4G communication system came to the market, there are ongoing efforts todevelop enhanced 5G communication systems or pre-5G communicationsystems. For the reasons, the 5G communication system or pre-5Gcommunication system is called the beyond 4G network communicationsystem or post LTE system.

For higher data transmit rates, 5G communication systems are consideredto be implemented on ultrahigh frequency bands (mmWave), such as, e.g.,60 GHz. To mitigate path loss on the ultrahigh frequency band andincrease the reach of radio waves, the following techniques are takeninto account for the 5G communication system: beamforming, massivemulti-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), arrayantenna, analog beamforming, and large scale antenna.

Also being developed are various technologies for the 5G communicationsystem to have an enhanced network, such as evolved or advanced smallcell, cloud radio access network (cloud RAN), ultra-dense network,device-to-device (D2D) communication, wireless backhaul, moving network,cooperative communication, coordinated multi-point (CoMP), andinterference cancellation.

There are also other various schemes under development for the 5G systemincluding, e.g., hybrid FSK and QAM modulation (FQAM) and sliding windowsuperposition coding (SWSC), which are advanced coding modulation (ACM)schemes, and filter bank multi-carrier (FBMC), non-orthogonal multipleaccess (NOMA) and sparse code multiple access (SCMA), which are advancedaccess schemes.

Meanwhile, a diversity of radio communication techniques is indevelopment by the growing information communication technology. Amongothers, the wireless local area network (WLAN) system enables wirelessaccess to the Internet in a home, business, or an area offering aparticular service through a personal digital assistant (PDA), a laptopcomputer, a portable multimedia player (PMP), or other portableterminals (hereinafter, referred to as a “WLAN terminal”) based on radiofrequency technology.

A mobile terminal equipped with a WLAN interface scans ambientaccessible WLAN access points (APs) while the WLAN interface stays on.

The scanning comes in two ways.

The first method is passive scanning.

In the passive scanning method, an AP periodically broadcasts beaconframes to the mobile terminal. Passive scanning consumes much more timethan active scanning does for hearing and thus passive scanning consumesten times more power than active scanning. In the case of passivescanning, the AP normally has a beacon period of 100 ms.

The second method is active scanning.

In the active scanning method, when a mobile terminal sends a request,an AP responds to the request. For active scanning, about 10 ms isrequired to scan one channel.

Such time gap causes passive scanning to consume much more power thanactive scanning.

As such, the wireless scanning process takes a long time, and thescanning process results in increased power consumption.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

According to the present disclosure, there are provided a scanningmethod and apparatus for a WLAN AP.

According to the present disclosure, there are provided a method andapparatus for minimizing power consumption caused by performing scanningon a WLAN AP.

According to an embodiment of the present disclosure, a method forscanning an access point (AP) by a first mobile terminal in a wirelesslocal area network (LAN) system comprises transmitting a request forWLAN AP information to a second mobile terminal positioned adjacent tothe first mobile terminal, obtaining the WLAN AP information from thesecond mobile terminal, and performing WLAN scanning based on the WLANAP information, wherein a number of channels where the WLAN scanning isperformed is smaller than a number of all channels for the AP scanning.

According to an embodiment of the present disclosure, an apparatus forscanning an access point (AP) by a first mobile terminal in a wirelesslocal area network (LAN) system comprises a controller configured toidentify the total number of channels for the AP scanning, to send arequest for WLAN AP information to a second mobile terminal positionedadjacent to the first mobile terminal, to obtain the WLAN AP informationfrom the second mobile terminal, and to perform WLAN scanning based onthe WLAN AP information, wherein a number of channels where the WLANscanning is performed is smaller than a number of all channels for theAP scanning.

According to an embodiment of the present disclosure, a method forscanning an access point (AP) by a second mobile terminal in a wirelesslocal area network (LAN) system comprises receiving a request for WLANAP information from a neighboring first mobile terminal, andtransmitting the WLAN AP information to the first mobile terminal,wherein the WLAN AP information determines a WLAN scanning operation bythe first mobile terminal, and wherein a number of channels where theWLAN scanning operation is performed is smaller than a number of allchannels for the AP scanning.

According to an embodiment of the present disclosure, an apparatus forscanning an access point (AP) by a second mobile terminal in a wirelesslocal area network (LAN) system comprises a controller configured toreceive a request for WLAN AP information from a neighboring firstmobile terminal and to transmit the WLAN AP information to the firstmobile terminal, wherein the WLAN AP information determines a WLANscanning operation by the first mobile terminal, and wherein a number ofchannels where the WLAN scanning operation is performed is smaller thana number of all channels for the AP scanning.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures, wherein:

FIG. 1 is a view illustrating an arrangement of a terminal to initiatescanning a WLAN AP and a mobile terminal that has already scanned a WLANAP adjacent to the terminal according to an embodiment of the presentdisclosure;

FIG. 2 is a flowchart illustrating a brief operating process of a mobileterminal according to an embodiment of the present disclosure;

FIG. 3 is a flowchart illustrating a process for obtaining informationon a WLAN AP from a neighbor mobile terminal using an independent basicservice set (IBSS) mode vendor specific action frame of a WLAN;

FIG. 4 is a flowchart illustrating a process for obtaining informationon a WLAN AP from a neighbor mobile terminal using an IBSS mode dataframe of a WLAN;

FIG. 5 is a flowchart illustrating an IBSS basic service set identifierBSSID provisioning process corresponding to operation 340 of FIG. 3 andoperation 440 of FIG. 4;

FIG. 6 is a flowchart illustrating a process for obtaining informationon a WLAN AP from a neighbor mobile terminal using a probe request/proberesponse frame of a WLAN;

FIG. 7 is a flowchart illustrating a method for scanning an AP in awireless LAN system according to an embodiment of the presentdisclosure;

FIG. 8 is a block diagram illustrating a communication unit for scanningan AP in a wireless LAN system according to an embodiment of the presentdisclosure;

FIG. 9 is a view illustrating a frame structure for scanning an AP in awireless LAN system according to an embodiment of the presentdisclosure; and

FIG. 10 is a flowchart illustrating a method for scanning an AP in awireless LAN system according to an embodiment of the presentdisclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are described indetail with reference to the accompanying drawings. The same referencedenotations may be used to refer to the same or similar elementsthroughout the specification and the drawings. When making the gist ofthe present disclosure unclear, the detailed description of knownfunctions or configurations is skipped.

The terms or language used herein should not be interpreted as limitedas typical ones or ones defined in the dictionary but rather to complywith the technical spirit of the present disclosure based on thedoctrine that the inventor may define terms on his own in a propermanner so as to make the invention understood in a best way to describebest the invention.

FIG. 1 is a view illustrating an arrangement of a terminal to initiatescanning a WLAN AP and a mobile terminal that has already scanned awireless local area network (WLAN) access points (AP) adjacent to theterminal according to an embodiment of the present disclosure.

Referring to FIG. 1, a first mobile terminal 110, having a communicationcoverage, moves from a position to a position as shown in FIG. 1 toperform a scanning procedures on nearby (or neighboring) wireless localarea network (WLAN) access points (APs) 105.

Meanwhile, a second mobile terminal 100 is positioned adjacent to thefirst mobile terminal 110, i.e., within the communication coverage ofthe first mobile terminal 110. The second mobile terminal 100 is assumedto perform the WLAN AP scanning procedure intended to be conducted bythe first mobile terminal 110 to store a result thereof. In this case,according to an embodiment of the present disclosure, the first mobileterminal 110, before performing the WLAN AP scanning procedure thatconsumes a considerable WLAN scanning time and energy, sends an inquiryabout the result of the WLAN AP scanning procedure to the second mobileterminal 100 and obtains a response therefrom, thereby shortening oromitting the WLAN AP scanning procedure.

FIG. 2 is a flowchart illustrating a WLAN AP scanning process of amobile terminal according to an embodiment of the present disclosure.

In the WLAN AP scanning process described in connection with FIG. 2,when there are N available WLAN channels (from channel 1 to channel N),it is assumed that a mobile terminal (e.g., the mobile terminal 110)sequentially scans the N WLAN channels (from channel 1 to channel N).Such sequence may exactly correspond to the channel numbers defined in,e.g., Institute of electrical and electronics engineers (IEEE) 802.11,but may also be logical channel numbers sorted in descending order ofthe chance that there is a WLAN AP by an enhanced mobile terminalimplementation.

The first mobile terminal 110 initiates a WLAN AP scanning process inoperation 200, and sets a scanning index (e.g., i) to 1. The firstmobile terminal 110 sends a request for WLAN AP information to aneighboring mobile terminal positioned on i-th channel, and waits for aresponse in operation 210. In some embodiments, the request may includefiltering conditions. Specifically, the filtering conditions may includeone or more APs of interest with respect to the first mobile terminal110 among APs covered by the second mobile terminal 100. The secondmobile terminal 100 may respond in a variety of ways. For example, insome embodiments, the second mobile terminal 100 may provide WLAN APinformation, or the channel information, that contains a channel, or achannel list, of an AP of interest with respect to the first mobileterminal 110 is located. In other embodiments, the second mobileterminal 100 may include in the WLAN AP information, or the channelinformation, content corresponding to overall information of a beaconframe. In still other embodiments, the second mobile terminal 100 mayinclude in the WLAN AP information, or the channel information probe,response frame transmitted from the AP of interest. The channelinformation may also include at least one of an address of the AP, aservice set identifier (SSID), and a media access control (MAC) addressof the AP. Further, the WLAN AP information may include AP capabilityinformation or a channel number.

In operation 220, when a predetermined timer expires, the first mobileterminal 110 determines whether the requested AP information from thesecond mobile terminal 100, a neighboring mobile terminal, has beenobtained. If it is determined the requested AP information from thesecond mobile terminal 100 has been obtained, the first mobile terminal110 goes to operation 240, otherwise to operation 230.

In operation 230, the first mobile terminal 110 changes or tunes theWLAN channel to a next channel and goes to operation 210 to send again arequest for WLAN AP information to the neighboring mobile terminal ofthe next channel.

In operation 240, the first mobile terminal 110 identifies whether theinformation on the WLAN AP obtained from the neighboring mobile terminalhas enough information to attempt association or immediate access to theWLAN AP. In some embodiments, the information provided from the secondmobile terminal 100 may be a number of the WLAN channel where the AP ispresent. In other embodiments, the information provided from the secondmobile terminal 100 may be a list of a plurality of channels to reducethe amount of data transmitted. In still other embodiments, theinformation provided from the second mobile terminal 100 may includecontents (e.g., the version of standard supported, data rate, or SSID)of the beacon frame or probe response frame transmitted from the AP.When the information is not enough to attempt access or association tothe WLAN AP, the first mobile terminal 110 goes to operation 250. Whenthe information is enough to attempt access or association to the WLANAP), the first mobile terminal 110 goes to operation 270 to store theobtained WLAN AP information together with the time obtained (e.g., atime stamp) in a memory (not shown) to respond to a future request forWLAN AP information sent from another neighboring mobile terminal to thefirst mobile terminal 110.

In operation 250, the first mobile terminal 110 scans, actively orpassively, on the channel obtained from the neighboring mobile terminalfor a probe response or beacon frame from the AP. In some embodiments,since the number of channels provided by the neighboring mobile terminalis generally much less than the total number N of channels available,the neighboring mobile terminal may significantly reduce the overallWLAN AP scanning time.

In operation 260, the first mobile terminal 110 determines whetherinformation enabling access or association to a desired AP has beenobtained as a result of the active scanning or passive scanningprocedure. In most cases, the first mobile terminal 110 may obtain theinformation enabling access or association to the desired AP throughactive scanning or passive scanning. However, after the neighboringmobile terminal obtains the AP information, as time elapses, the APinformation may be varied (e.g., the AP's operation channel is varied orAP's traffic load is increased). As a result, the first mobile terminal110 might fail to obtain the information on the desired AP. Whenobtaining the information that enables access or association to thedesired AP, the first mobile terminal 110 goes to operation 270 to storethe obtained WLAN AP information together with the time obtained in thememory to respond to a future request for WLAN AP information sent fromanother neighboring mobile terminal.

When failing to obtain the information enabling access or association tothe desired AP in operation 260, the first mobile terminal 110 goes tooperation 280 to perform a normal scanning process on all the channels.The first mobile terminal 110 stores the result of the process togetherwith the WLAN AP information obtained in operation 270 in the memory torespond to a future request for WLAN AP information sent from anotherneighboring mobile terminal.

In operation 290, the terminal terminates the scanning process, followedby an access or association procedure.

FIG. 3 is a flowchart illustrating a process for obtaining informationon a WLAN AP from a neighbor mobile terminal using an independent basicservice set (IBSS) mode vendor specific action frame of a WLAN.

It is assumed that there are a plurality of mobile terminals and APsadjacent to the first mobile terminal 110. It is assumed that a mobileterminal 312 and an AP 311 are not implemented with a function accordingto the present disclosure are present on WLAN channel 1. It is alsoassumed that a mobile terminal 100 (e.g., the second mobile terminal 100of FIG. 1) and an AP 321 that are implemented with an embodiment of thepresent disclosure are present on WLAN channel 2. Further, it is assumedthat an AP 330 intended to be accessed by the first mobile terminal 110is present on channel k.

Although FIG. 3 shows that each of channel 1 and channel 2 includes oneterminal and one AP, each of the channels may include a plurality ofmobile terminals and/or APs in other embodiments. Further, channel k mayindicate any channel where a desired AP to be accessed by the firstmobile terminal 110. In some embodiments, channel k may also be the sameas channel 1 or channel 2. In other embodiments, channel k may also be agroup of multiple channels, rather than a single channel.

The first mobile terminal 110 intending to scan WLAN APs via an ambientmobile terminal determines a common IBSS basic service set identifier(BSSID) for direct communication with the ambient mobile terminal,without involvement by the WLAN AP. In some cases, a typical mobileterminal arbitrarily determines a BSSID and broadcasts the same viatypical WLAN inter-terminal direct communication (e.g., Adhoccommunication). However, this is time-consuming. Rather, a scheme to useprevious provisioning of a BSSID upon requesting AP information betweenmobile terminals using over the air (OTA) provisioning is disclosed. Themessage exchange in the OTA provisioning procedure may be conductedusing messages specified in relevant standards, such as open mobilealliance device management (OMA DM) and transport layer security (TLS),and this is described below in further detail with reference to FIG. 5.

Specifically, as shown in FIG. 5, the first mobile terminal 110 performsIBSS BSSID provisioning with the second mobile terminal 100 in operation340.

The first mobile terminal 110 broadcasts an IBSS mode vendor specificaction frame (e.g., Type: 00, Subtype: 1101) including an AP informationrequest to the second mobile terminal 100 of channel 2 in operation 340.In this case, the BSSID of this frame uses the BSSID of the IBSSprovisioned in operation 340.

The vendor specific action frame in operation 341 is a broadcast-typeframe, thus causing a potential overhead from all ambient mobileterminals receiving the same responses. In operation 342, after apredetermined amount of time as determined in operation 341 a, theneighboring mobile terminal or the second mobile terminal 100 receivesthe broadcast frame. In some embodiments, two or more schemes areavailable to minimize the size and number of broadcast messages to beadditionally generated.

For example, in a first scheme, transmit power is limited so thatneighboring mobile terminals positioned near the first mobile terminal110 only may receive an AP Information Request. For transmitting an APInformation Request within a WLAN, a transmit power limiting rule fornon-licensed bands is typically used to limit the maximum transmitpower. By limiting the transmit power to be less than the maximumtransmit power, only the very close neighboring mobile terminals mayreceive the AP Information Request. Thus, no response to an APInformation Request from any mobile terminal may be attributed toexcessive low transmit power. Accordingly, higher transmit power may beused to broadcast a next AP Information Request.

Further, in a second scheme, an AP Information Request containing afiltering condition is broadcast so that only neighboring mobileterminals meeting the filtering condition may respond to the APInformation Request. The filtering condition may contain one or more ofthe following:

Elapsed time after scanning: A WLAN AP may vary parameters such asoperation channels depending on variations in ambient radioenvironments, so as to prevent a neighboring mobile terminal fromresponding after a predetermined amount of time has elapsed.

Channel number or channel range: This allows for receiving responsesfrom only neighboring mobile terminals that have AP informationcorresponding to a particular channel or channel range that the firstmobile terminal 110 may need.

Reception signal strength threshold: This allows for receiving aresponse from only neighboring mobile terminals that have a receptionstrength of AP Information Request higher than a predefined threshold.Thus, only neighboring mobile terminals positioned close to the firstmobile terminal 110 (thus having higher reception strength) may respond.

Particular address: This allows for receiving a response from onlyneighboring mobile terminals that has AP information with a particularaddress (e.g., an SSID, BSSID, ESSID, or homogenous extended service setID (HESSID)) or a prefix of an address.

BSS Load threshold: This allows for receiving a response from onlyneighboring mobile terminals that have AP information whose BSS load islarger than a predefined threshold.

Backhaul rate threshold: This allows for receiving a response from onlyneighboring mobile terminals that have AP information whose backhaulrate is larger than a predefined threshold.

AP capability: This allows for receiving a response from onlyneighboring mobile terminals that have AP information with a particularcapability (e.g., a very high throughput (VHT) capability).

Sorting reference: This informs a sorting reference metric when aneighboring mobile terminal responds with a plurality of AP information.

As such, the first mobile terminal 110 broadcasts an IBSS mode vendorspecific action frame including the AP Information Request on channel 1and then waits to respond in operation 341. Since there are no terminalswhere an embodiment of the present disclosure is implemented on channel1, a response may not be obtained. After a predetermined time elapses,the first mobile terminal 110 terminates the operation on channel 1.

In operation 342, the first mobile terminal 110 broadcasts an IBSS modevendor specific action frame including an AP Information Request on anext channel (e.g., channel 2). When receiving the same, the secondmobile terminal 100 responds with an IBSS mode vendor specific actionframe containing an AP Information Response in operation 343. The vendorspecific action frame may be of broadcast type or unicast type. When thevendor specific action frame is implemented as a broadcast type, anotherrequesting mobile terminal receiving the AP information response may notneed to transmit the AP information request.

The AP information response may come in two types.

A first type of AP information response may be a WLAN channel number, ora list of a plurality of channels, where an AP meeting the filteringcondition included in the AP information request is present.

A second type of AP information response may include content of thebeacon response frame or probe response frame (e.g., version ofsupported standard, data rate, or SSID) that has been transmitted by theAP meeting the filtering condition included in the AP informationrequest.

As in operation 343 a, when the AP information response contains a WLANchannel number or a list of multiple channels after a predeterminedtime, the first mobile terminal 110 actively or passively scans thechannel or the list of channels in operation 350.

When the AP information response contains the content of the beaconresponse frame or probe response frame previously transmitted by the AP,the first mobile terminal 110 does not need additional active or passivescanning. As a result, the first mobile terminal 110 attempts an accessor association procedure in operation 360.

Meanwhile, although not directly shown in FIG. 3, when a remainingbattery power of the second mobile terminal 100 is low after receivingan AP information request, the second mobile terminal 100 may notrespond with an AP information response in order to save power.

FIG. 4 is a flowchart illustrating a process for obtaining informationon a WLAN AP from a neighbor mobile terminal using an IBSS mode dataframe of a WLAN.

It is assumed that there are a plurality of mobile terminals and APsadjacent to the first mobile terminal 110. It is assumed that a mobileterminal 312 and an AP 311 that are not implemented with a functionaccording to the present disclosure are present on WLAN channel 1. It isalso assumed that a second mobile terminal 100 (e.g., the second mobileterminal 100 of FIG. 1) and an AP 321 that are implemented with anembodiment of the present disclosure are present on WLAN channel 2.Further, it is assumed that an AP 330 intended to be accessed by thefirst mobile terminal 110 is present on channel k.

Although FIG. 4 shows that each of channel 1 and channel 2 includes oneterminal and one AP, each of the channels may include a plurality ofmobile terminals and/or APs in other embodiments. Further, channel k mayindicate any channel where a desired AP to be accessed by the firstmobile terminal 110. In some embodiments, channel k may also be the sameas channel 1 or channel 2. In other embodiments, channel k may also be agroup of multiple channels, rather than a single channel.

The first mobile terminal 110 intending to scan WLAN APs via an ambientmobile terminal determines a common IBSS basic service set identifier(BSSID) for direct communication with the ambient mobile terminal,without involvement by the WLAN AP. In some cases, a typical mobileterminal arbitrarily determines a BSSID and broadcasts the same viatypical WLAN inter-terminal direct communication (e.g., Adhoccommunication). However, this is time-consuming. Rather, a scheme to useprevious provisioning of a BSSID upon requesting AP information betweenmobile terminals using over the air (OTA) provisioning is disclosed. Themessage exchange in the OTA provisioning procedure may be conductedusing messages specified in relevant standards, such as open mobilealliance device management (OMA DM) and transport layer security (TLS),and this is described below in further detail with reference to FIG. 5.

The first mobile terminal 110 performs IBSS BSSID provisioning with thesecond mobile terminal 100 in operation 440.

In operation 441, an IBSS mode data frame (e.g., type: 10) including anAP information request is broadcast on channel 1. In this case, theBSSID of this frame uses the BSSID of the IBSS provisioned in operation340.

The IBSS mode data frame in operation 441 is a broadcast-type frame,thus causing a potential overhead from all ambient mobile terminalsreceiving the same responses. After the neighboring mobile terminalreceives the broadcast frame, the present disclosure proposes twoschemes to minimize the size and number of messages to be additionallygenerated.

For example, in a first scheme, transmit power is limited so thatneighboring mobile terminals positioned near the first mobile terminal110 only may receive an AP Information Request. For transmitting an APInformation Request within a WLAN, a transmit power limiting rule fornon-licensed bands is typically used to limit the maximum transmitpower. By limiting the transmit power to be less than the maximumtransmit power, only the very close neighboring mobile terminals mayreceive the AP Information Request. Thus, no response to an APInformation Request from any mobile terminal may be attributed toexcessive low transmit power. Accordingly, higher transmit power may beused to broadcast a next AP Information Request.

Further, in a second scheme, an AP Information Request containing afiltering condition so that only neighboring mobile terminals meetingthe particular condition may respond to the AP Information Request. Thefiltering condition may contain one or more of the following:

Elapsed time after scanning: A WLAN AP may vary parameters such asoperation channels depending on variations in ambient radioenvironments, so as to prevent a neighboring mobile terminal fromresponding after a predetermined amount of time has elapsed.

Channel number or channel range: This allows for a response from onlyneighboring mobile terminals that have AP information corresponding to aparticular channel or channel range in which the first mobile terminal110 may need.

Reception signal strength threshold: This allows for receiving aresponse from only neighboring mobile terminals having a receptionstrength of AP Information Request higher than a predefined threshold.Thus, only neighboring mobile terminals positioned close to the firstmobile terminal 110 (thus having higher reception strength) may respond.

Particular address: This allows for receiving a response from onlyneighboring mobile terminals that have a particular address (e.g., aservice set identification (SSID), basic service set identification(BSSID), extended service set identification (ESSID), or homogeneousextended service set ID (HESSID)) or a prefix of an address.

BSS Load threshold: This allows for receiving a response from onlyneighboring mobile terminals that AP information whose BSS load islarger than a predefined threshold.

Backhaul rate threshold: This allows for receiving a response from onlyneighboring mobile terminals that have AP information whose backhaulrate is larger than a predefined threshold.

AP capability: This allows for receiving a response from onlyneighboring mobile terminals that have AP information with a particularcapability (e.g., VHT capability).

Sorting reference: This informs a sorting reference metric when aneighboring mobile terminal responds with a plurality of AP information.

As such, the first mobile terminal 110 broadcasts an IBSS mode dataframe including the AP Information Request on channel 1 and then waitsto respond in operation 441. Since there are no terminals where thecontent of the present disclosure is implemented on channel 1, aresponse may not be obtained. no respond might be obtained. After apredetermined time elapses, the first mobile terminal 110 terminates theoperation on channel 1.

In operation 442, the first mobile terminal 110 broadcasts an IBSS modedata frame including an AP Information Request on a next channel(channel 2) after a predetermined time as in operation 441 a. Whenreceiving the same, the second mobile terminal 100 responds with an IBSSmode vendor specific data frame containing an AP Information Response inoperation 443. The IBSS mode vendor specific data frame may be ofbroadcast type or unicast type. When the IBSS mode vendor specific dataframe is implemented as a broadcast type, another requesting mobileterminal receiving the AP information response may not need to transmitthe AP information request.

The AP information response greatly comes in two types.

A first type of AP information response may be a WLAN channel number, ora list of a plurality of channels, where an AP meeting the filteringcondition included in the AP information request is present.

A second type of AP information response may include content of thebeacon response frame or probe response frame (e.g., version ofsupported standard, data rate, or SSID) that has been transmitted by theAP meeting the filtering condition included in the AP informationrequest.

As in operation 443 a, when the AP information response contains a WLANchannel number, or a list of multiple channels after a predeterminedtime, the first mobile terminal 110 actively or passively scans thechannel or the list of channels in operation 350.

When the AP information response contains the content of the beaconresponse frame or probe response frame previously transmitted by the AP,the first mobile terminal 110 does not need additional active or passivescanning. As a result, the first mobile terminal 110 attempts an accessor association procedure in operation 360.

Meanwhile, although not directly shown in FIG. 4, when the remainingbattery power of the second mobile terminal 100 is low after receivingthe AP information request, the second mobile terminal 100 may notrespond with an AP information response in order to save power.

FIG. 5 is a flowchart illustrating an IBSS BSSID provisioning processcorresponding to operation 340 of FIG. 3 and operation 440 of FIG. 4.

The first mobile terminal 110 intending to scan WLAN APs via an ambientmobile terminal first determines a common IBSS basic service setidentifier (BSSID) for direct communication with the ambient mobileterminal, without involvement by the WLAN AP. Although in a typical WLANinter-terminal direct communication (e.g., Adhoc communication), onlyone mobile terminal arbitrarily determines a BSSID to broadcast, thisapproaches is time-consuming. Accordingly, in an embodiment of thepresent disclosure, previous provisioning of a BSSID upon requesting APinformation between terminals using OTA provisioning may be used.

Message exchange in the OTA provisioning procedure may be conductedusing relevant protocols such as OMA DM and transport layer security(TLS).

In operation 540, which is optional, when provisioning messages areexchanged using a TLS communication protocol, a TLS sessionestablishment process between the first mobile terminal 110 and aprovisioning server 530 may be performed. The detailed TLS sessionestablishment procedure is well known to one of ordinary skill in theart, and thus, no further detailed description thereof is given.

In operation 541, the first mobile terminal 110 transfers, to theprovisioning server 530, a provisioning request message for requestingto provision an IBSS BSSID. The provisioning request message mayselectively include a device manufacturer ID and an authentication key.

The provisioning server 530 transfers a configuration message to thefirst mobile terminal 110 in operation 542. The configuration messagemay contain an IBSS BSSID for Adhoc communication between mobileterminals and may optionally include, e.g., an authentication key.

FIG. 6 is a flowchart illustrating a process for obtaining informationon a WLAN AP from a neighbor mobile terminal using a probe request/proberesponse frame of a WLAN.

It is assumed that there are a plurality of mobile terminals and APsadjacent to the first mobile terminal 110. It is assumed that a mobileterminal 312 and an AP 311 that are not implemented with a functionaccording to the present disclosure are present on WLAN channel 1. It isalso assumed that a second mobile terminal 100 (e.g., the second mobileterminal 100 of FIG. 1) and an AP 321 that are implemented with anembodiment of the present disclosure are present on WLAN channel 2.Further, it is assumed that an AP 330 intended to be accessed by thefirst mobile terminal 110 is present on channel k.

Although FIG. 6 shows that each of channel 1 and channel 2 includes oneterminal and one AP, each of the channels may include a plurality ofmobile terminals and/or APs in other embodiments. Further, channel k mayindicate any channel where a desired AP to be accessed by the firstmobile terminal 110. In some embodiments, channel k may also be the sameas channel 1 or channel 2. In other embodiments, channel k may also be agroup of multiple channels, rather than a single channel.

In operation 641, a probe request frame (e.g., type: 00, subtype: 0100)including an AP information request is broadcast on channel 1. In thiscase, the AP information request is transferred using the vendorspecific field of the probe request.

After receiving the broadcast frame, the AP 311 may not respond to theAP information request. However, as in operation 642, the AP 311transmits an AP information response as a message responding to the APinformation request.

Although not directly shown in FIG. 6, after receiving the broadcastframe, the mobile terminal 312 might not respond to the AP informationrequest. However, as in operation 642, the mobile terminal 312 maytransmit an AP information response as a message responding to the APinformation request.

After a predetermined amount of time has elapsed in operation 642 a, thefirst mobile terminal 110 receiving the AP information response, whenthe AP information response does not contain the desired AP information,broadcasts a probe request frame (e.g., type: 00, subtype: 0100)including an AP information request on channel 2 in operation 643. Inthis case, the AP information request is transferred using the vendorspecific field of the probe request.

After receiving the broadcast frame, the second mobile terminal 100might not respond to the AP information request. However, as inoperation 644, the second mobile terminal 100 may transmit an APinformation response as a message responding to the AP informationrequest.

After receiving the broadcast frame, the AP 321 might not respond to theAP information request. However, as in operation 645, the AP 321 maytransmit an AP information response as a message responding to the APinformation request.

When the AP information response contains a WLAN channel number or listof multiple channels after a predetermined time (operation 645 a), thefirst mobile terminal 110 performs active scanning or passive scanningon the channel or multiple channels in operation 350.

When the AP information response contains the content of thebeacon/probe response frame previously transmitted by the AP, the firstmobile terminal 110 does not need additional active scanning or passivescanning procedure, and thus, the first mobile terminal 110 attempts anaccess or association procedure in operation 360.

FIG. 7 is a flowchart illustrating a method for scanning an AP in awireless LAN system according to an embodiment of the presentdisclosure.

The first mobile terminal 110 makes a Bluetooth connection with thesecond mobile terminal 100.

When the Bluetooth connection is made, the first mobile terminal 110transmits an AP information request message to the second mobileterminal 100 through Bluetooth data in operation 721. The second mobileterminal 100 transmits an AP information response message throughBluetooth data. The AP information response message contains informationon a WLAN AP pre-scanned by the second mobile terminal 100.

When the AP information response contains a WLAN channel number or listof multiple channels after a predetermined time (not shown in thedrawings), the first mobile terminal 110 performs active scanning orpassive scanning on the channel or multiple channels in operation 350.

When the AP information response contains the content of thebeacon/probe response frame previously transmitted by the AP, the firstmobile terminal 110 does not need additional active scanning or passivescanning procedure, and thus, the first mobile terminal 110 attempts anaccess or association procedure in operation 360.

FIG. 8 is a block diagram illustrating a communication unit for scanningan AP in a wireless LAN system according to an embodiment of the presentdisclosure.

As shown in FIG. 8, reference numeral 810 denotes the first mobileterminal 110 of FIG. 1, and reference numeral 820 denotes the secondmobile terminal 100 of FIG. 1.

A Wi-Fi transceiver 813 of the first mobile terminal 810 and the Wi-Fitransceiver 823 of the second mobile terminal 820 communicate a proberequest, a probe response, an Independent Basic Service Set (IBSS) modevendor specific action, and an IBSS mode data frame. The communicationsbetween the Wi-Fi transceiver 813 and the Wi-Fi transceiver 823 maycorrespond to, e.g., operations 341, 342, and 343 of FIG. 3, operations441, 442, and 443 of FIG. 4, and operations 641, 642, 643, 644, and 645of FIG. 6.

The BT transceiver 815 of the first mobile terminal 810 and the BTtransceiver 825 of the second mobile terminal 820 communicate BT-relateddata. The communications between the BT transceiver 815 and the BTtransceiver 825 may correspond to, e.g., operations 721 and 722 of FIG.7.

When the Wi-Fi transceiver 813 of the first mobile terminal 810 and theWi-Fi transceiver 823 of the second mobile terminal 820 exchangeinformation using management-type frames, such as a probe request, proberesponse, or an IBSS mode vendor specific action frame, a Wi-Ficonnection control unit 811 and the Wi-Fi transceiver 813 maycommunicate with each other using an MLME-SCAN.request( ) primitive andMLME-SCAN.config( ) primitive. In this case, the Wi-Fi connectioncontrol unit 811 may designate a specific type of frame to be used bythe Wi-Fi transceiver 813 in the MLME-SCAN.request( ) as a parameter.When there are no special parameters, a particular type of frame may bedetermined by the Wi-Fi transceiver 813. When the Wi-Fi transceiver 813of the first mobile terminal 810 and the Wi-Fi transceiver 823 of thesecond mobile terminal 820 exchange information using frames of a datatype such as an IBSS mode data frame, the Wi-Fi connection control unit811 may communicate with the Wi-Fi transceiver 813 using anMA-UNITDATA.request( ), MA-UNITDATA-STATUS.indication( ), andMA-UNITDATA.indication( ) primitives.

Meanwhile, the Wi-Fi connection control unit 811 and BT transceiver 815of the first mobile terminal 810 and the Wi-Fi connection control unit821 and BT transceiver 825 of the second mobile terminal 820, whencommunicating information using BT data frames, may communicate witheach other using an L2CA_Request, L2CA_Confirm, L2CA_Indication, andL2CA_Response primitive.

FIG. 9 is a view illustrating a frame structure for scanning an AP in awireless LAN system according to an embodiment of the presentdisclosure.

Referring to FIG. 9, the frame structure includes an MAC header 910, aframe body 920, and a frame check sequence (FCS) 930.

The MAC header 910 includes a frame control 911. The frame control 911,as shown in FIG. 9, includes control information regarding a proberequest, a probe response, an intra-IBSS action, and intra-IBSS data.

The vendor specific field in the probe request has the type set to,e.g., “00,” and the subtype set to “0100.”

In the case the IBSS mode data frame included in the AP informationrequest, the type is set to, e.g., “10.”

The frame body field 920 includes a fragment number field (not shown inthe drawings), a vendor specific field 921, and an IBSS mode data frame(not shown in the drawings). The frame body field 920 may furtherinclude a basic service set identification (SSID) field, a supportedrates field, a request information field, and an extended supportedrates field. The SSID field indicates an identification of a BSS orIBSS, and the supported rates field indicates supportable data rates.The information on the supportable data rates, as necessary, may beselectively included in the extended supported rates field.

Further, the request information field may be used to allow a deviceresponsive to the probe request frame to request information to beincluded in the probe response frame.

The FCS field 930 may include cyclic redundancy check (CRC) informationregarding frame error correction.

FIG. 10 is a flowchart illustrating a method for scanning an AP in awireless LAN system according to an embodiment of the presentdisclosure.

Referring to FIG. 10, in operations 1001 and 1002, APs on channel 1broadcast beacon messages to the first mobile terminal.

In operations 1003 and 1004, APs on channel N broadcast beacon messagesto the first mobile terminal.

Operations 1001 to 1004 are directed to a passive scanning method inwhich an AP periodically broadcasts beacon frames to the first mobileterminal.

Referring to FIG. 10, in operation 1101, the first mobile terminaltransmits probe request messages to APs on channel 1. Then, the APs onchannel 1 transmit probe response messages to the first mobile terminalresponsive to the probe request messages as in operations 1102 and 1103.

Likewise, referring to FIG. 10, in operation 1104, the first mobileterminal transmits probe request messages to APs on channel N. Then, theAPs on channel N transmit probe response messages to the first mobileterminal responsive to the probe request messages as in operations 1105and 1106.

Operations 1101 to 1106 of FIG. 10 are directed to an active scanningmethod in which when the first mobile terminal requests, an AP responds.

A method and apparatus for scanning an AP in a wireless LAN systemaccording to an embodiment of the present disclosure may be implementedin hardware, software, or a combination of hardware and software. Suchsoftware may be stored in a volatile or non-volatile storage device suchas a read-only memory (ROM) or other storage devices, a memory, such asa random access memory (RAM), a memory chip, a device or an integratedcircuit, or a storage medium, such as, e.g., a compact disc (CD), adigital video disc (DVD), a magnetic disk, or a magnetic tape, whichallows for optical or magnetic recording while simultaneously read outby a machine (e.g., a computer). A method for scanning an AP in awireless LAN system according to an embodiment of the present disclosuremay be implemented by a computer or portable terminal including acontroller and a memory, and the memory may be an example of a storagemedium that may be read out by a machine appropriate to store a programor programs including instructions for realizing the embodiments of thepresent disclosure.

Accordingly, the present disclosure encompasses a program containingcodes for implementing the device or method set forth in the claims ofthis disclosure and a machine (e.g., computer)-readable storage mediumstoring the program. The program may be electronically transferred viaany media such as communication signals transmitted through a wired orwireless connection and the present disclosure properly includes theequivalents thereof.

An apparatus for scanning an AP in a wireless LAN system according toembodiments of the present disclosure may receive the program from aprogram providing device wiredly or wirelessly connected thereto andstore the same. The program providing device may include a memory forstoring a program including instructions to enable the programprocessing device to perform a method for scanning an AP in a presetwireless LAN system and information necessary for the method forscanning an AP in a wireless LAN system, a communication unit forperforming wired or wireless communication with the program processingdevice, and a controller transmitting the program to the communicationdevice automatically or at the request of the program processing device.

As is apparent from the foregoing description, the present disclosuremay minimize power consumption caused by performing scanning on a WLANAP.

Although specific embodiments of the present disclosure have beendescribed above, various changes may be made thereto without departingfrom the scope of the present disclosure. Thus, the scope of the presentdisclosure should not be limited to the above-described embodiments, andshould rather be defined by the following claims and equivalentsthereof.

What is claimed is:
 1. A method for scanning an access point (AP) by afirst mobile terminal in a wireless local area network (LAN) system, themethod comprising: transmitting a request for WLAN AP information to asecond mobile terminal positioned adjacent to the first mobile terminal;obtaining the WLAN AP information from the second mobile terminal; andperforming WLAN scanning based on the WLAN AP information, wherein anumber of channels where the WLAN scanning is performed is smaller thana number of all channels for the AP scanning.
 2. The method as claimedin claim 1, wherein the WLAN AP information includes channel informationwhere an AP of interest with respect to the first mobile terminal ispresent.
 3. The method as claimed in claim 1, wherein the channelinformation includes at least one of a WLAN channel number where an APis present, and a list of multiple channels where an AP is present. 4.The method as claimed in claim 3, wherein the channel informationincludes at least one of an address of an AP, a service set identifier(SSID), and a media access control (MAC) address of an AP.
 5. The methodas claimed in claim 1, wherein the WLAN AP information includes acontent corresponding to overall information of at least one of a beaconframe and a probe response frame transmitted to the second mobileterminal from the AP of interest with respect to the first mobileterminal.
 6. The method as claimed in claim 1, further comprising:determining whether the WLAN AP information is information enablingattempt to access or associate to a WLAN AP; when the WLAN APinformation does not include the information enabling attempt to accessor associate to the WLAN AP, performing WLAN scanning on a number ofchannels, wherein the number is reduced by the WLAN AP information; andwhen the WLAN AP information includes the information enabling attemptto access or associate to the WLAN AP, storing the obtained WLAN APinformation and a time that the WLAN AP information is obtained.
 7. Anapparatus for scanning an access point (AP) by a first mobile terminalin a wireless local area network (LAN) system, the apparatus comprisinga controller configured to identify a total number of channels for theAP scanning, to send a request for WLAN AP information to a secondmobile terminal positioned adjacent to the first mobile terminal, toobtain the WLAN AP information from the second mobile terminal, and toperform WLAN scanning based on the WLAN AP information, wherein a numberof channels where the WLAN scanning is performed is smaller than thetotal number of channels for the AP scanning.
 8. The apparatus asclaimed in claim 7, wherein the WLAN AP information includes channelinformation where an AP of interest with respect to the first mobileterminal is present.
 9. The apparatus as claimed in claim 7, wherein thechannel information includes at least one of a WLAN channel number wherean AP is present, and a list of multiple channels where an AP ispresent.
 10. The apparatus as claimed in claim 9, wherein the channelinformation includes at least one of an address of an AP, a service setidentifier (SSID), and a media access control (MAC) address of an AP.11. The apparatus as claimed in claim 7, wherein the WLAN AP informationincludes a content corresponding to overall information of at least oneof a beacon frame and a probe response frame transmitted to the secondmobile from the AP of interest with respect to the first mobileterminal.
 12. The apparatus as claimed in claim 7, wherein thecontroller is configured to determine whether the WLAN AP information isinformation enabling attempt to access or associate to a WLAN AP; whenthe WLAN AP information does not include the information enablingattempt to access or associate to the WLAN AP, to perform WLAN scanningon channels wherein the number is reduced by the WLAN AP information;and when the WLAN AP information includes the information enablingattempt to access or associate to the WLAN AP, to store obtained WLAN APinformation and a time that the WLAN AP information is obtained.
 13. Amethod for scanning an access point (AP) by a second mobile terminal ina wireless local area network (WLAN) system, the method comprising:receiving a request for WLAN AP information from a neighboring firstmobile terminal; and transmitting the WLAN AP information to the firstmobile terminal, wherein the WLAN AP information determines a WLANscanning operation by the first mobile terminal, and wherein a number ofchannels where the WLAN scanning operation is performed is smaller thana number of all channels for the AP scanning.
 14. The method as claimedin claim 13, wherein the WLAN AP information includes channelinformation where an AP of interest with respect to the first mobileterminal is present.
 15. The method as claimed in claim 13, wherein thechannel information includes at least one of a WLAN channel number wherean AP is present, and a list of multiple channels where an AP ispresent.
 16. The method as claimed in claim 15, wherein the channelinformation includes at least one of an address of an AP, a service setidentifier (SSID), and a media access control (MAC) address of an AP.17. The method as claimed in claim 13, wherein the WLAN AP informationincludes a content corresponding to overall information of at least oneof a beacon frame and a probe response frame transmitted to the secondmobile terminal from the AP of interest with respect to the first mobileterminal.
 18. An apparatus for scanning an access point (AP) by a secondmobile terminal in a wireless local area network (LAN) system, theapparatus comprising a controller configured to receive a request forWLAN AP information from a neighboring first mobile terminal and totransmit the WLAN AP information to the first mobile terminal, whereinthe WLAN AP information determines a WLAN scanning operation by thefirst mobile terminal, and wherein a number of channels where the WLANscanning operation is performed is smaller than a number of all channelsfor the AP scanning.
 19. The apparatus as claimed in claim 18, whereinthe WLAN AP information includes channel information where an AP ofinterest with respect to the first mobile terminal is present.
 20. Theapparatus as claimed in claim 18, wherein the channel informationincludes at least one of a WLAN channel number where an AP is present,and a list of multiple channels where an AP is present.
 21. Theapparatus as claimed in claim 20, wherein the channel informationincludes at least one of an address of an AP, a service set identifier(SSID), and a media access control (MAC) address of an AP.
 22. Theapparatus as claimed in claim 18, wherein the WLAN AP informationincludes a content corresponding to overall information of at least oneof a beacon frame and a probe response frame transmitted to the secondmobile from the AP of interest with respect to the first mobileterminal.
 23. The apparatus as claimed in claim 18, wherein thecontroller is configured to determine whether the WLAN AP information isinformation enabling attempt to access or associate to a WLAN AP, andwhen the WLAN AP information is not the information enabling attempt toaccess or associate to the WLAN AP, to perform WLAN scanning on channelswhose number is reduced by the WLAN AP information.